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Synthesis of the Thio‐Linked Ganglioside GM 3 epitope
Author(s) -
Eisele Thomas,
Schmidt Richard R.
Publication year - 1997
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199719970512
Subject(s) - chemistry , glycosylation , neuraminic acid , trifluoromethanesulfonate , stereochemistry , sialic acid , thio , epitope , catalysis , biochemistry , antigen , biology , genetics
The synthesis of sulfur‐linked GM 3 epitope 2 is based on acid‐catalyzed and base‐promoted S ‐glycosylation processes. As a precursor, 2‐ O ‐benzoyl‐3‐thiogalactoside 10 was required, and was obtained from 4,6‐ O ‐benzylidene‐galactoside 3 in six high‐yielding steps. Base‐promoted S ‐glycosylation of 10 with neuraminic acid functionalized β‐halogenose 11 in the presence of NaH as base and Kryptofix 21 as coactivator afforded α(2‐3)‐thio‐linked disaccharide 13 , which was readily converted to α‐halogenose 20 . Heptyl 1‐thioglycoside 22 was obtained from O ‐galactosyl trichloroacetimidate 21 and heptylthiol via acid‐catalyzed S ‐glycosylation. 22 was transformed into 2,3,6‐tri‐ O ‐acylgalactoside 26 which, via the 4‐ O ‐triflate and treatment with potassium thioacetate, followed by selective removal of the S ‐acetyl group, furnished the 2,3,6‐tri‐ O ‐acyl‐4‐thioglucoside 28 . Base‐promoted S ‐glycosylation of 28 with halogenose 20 led to fully acylated target molecule 29 , which was quantitatively converted into 2 .